A highly sensitive enzyme immunoassay for mouse beta nerve growth factor.

A sensitive two-site enzyme immunoassay system for mouse beta nerve growth factor (NGF) was developed, based on the sandwiching of the antigen between anti-mouse beta NGF antibody IgG coated to a polystyrene tube and anti-mouse beta NGF antibody Fab'-linked beta-D-galactosidase (beta-D-galactoside hydrolase, EC 3.2.1.23). This method has the following advantages: (a) the procedures are simple and rapid compared to bioassay or two-site radioimmunoassay; (b) antibody Fab'-beta-D-galactosidase complex is more stable than 125I-labeled antibody; (c) purified beta NGF is detectable at a concentration as low as 10 pg/ml. Our enzyme immunoassay was used to examine the levels of NGF in some tissues of mice. The submaxillary gland contained a high concentration of NGF. However, other tissues, such as the heart, brain, and skeletal muscle, and serum did not contain detectable NGF. These results support recent findings by other investigators that NGF was not found in the organs/tissues other than the submaxillary gland of mice.